1 Cook the tomato paste: Heat a large, heavy-bottomed pot or Dutch oven over medium-high heat. Add the tomato paste to the dry pot and cook, constantly scraping the bottom with a wooden spoon or silicone spatula, until the tomato smells rich and toasty and you start to see browned (not burned) patches in the bottom of the pot. This should take 1 to 3 minutes.
2 Combine the ingredients in a pot: Remove the pot from heat and add the ground beef and water. Mix them together into a sludge. It will not look pretty, but press on. There’s a method to this madness.
Return to medium-high heat and bring to a simmer, stirring all the while, so the sludge breaks up into a mealy paste. Add all the remaining ingredients except the vinegar and chocolate.
3 Simmer gently, uncovered, for 2 to 3 hours: Stir the chili often. You want the volume to reduce a bit. (To be honest, just one hour of cook time is okay, but for optimal chili-ness, go long.)
4 Cool to room temperature, then refrigerate overnight. Refrigerate in an air-tight covered container. (Note: you can eat the chili immediately if you want to.)
5 De-fat the chili: The next day, lift or scrape off any solidified fat from the top of the chili and discard.
6 Warm and serve: Bring to a rapid simmer, then add the vinegar and chocolate. (The chocolate won’t make it taste sweet—it adds a hint of sophisticated complexity and acts as a foil for all those spices.)
Serve any “way” (see headnotes). The chili will also keep refrigerated for up to a week or frozen for up to a year.